1. Field of the Invention
The present invention relates in general to rail cars, and in particular to rail cars which are utilized for carrying bulky items ranging from lumber and drywall to steel bars.
2. Description of the Prior Art
In the prior art, a certain type of railcar, which is known as a "centerbeam railcar," is utilized to carrying lumber and drywall. Because the loads are relatively light, the centerbeam railcar need not be excessively reinforced. Additionally, centerbeam railcars are not generally useful for carrying steel beams or other similar heavy loads, since the loading requirement for a steel-carrying railcar is substantially greater than that of lumber-carrying railcars.
In a centerbeam car, a central partition is provided which runs along the longitudinal axis of the railcar between relatively lightweight bulkheads. A structural section is provided which is generally horizontal to the bed of the car. This horizontal structural section is referred to as the "top section." In the prior art, the top section is about three feet wide, runs the full length of the car, and serves to give the car much of its lateral stiffness, vertical bending stiffness, and torsional stiffness. However, the horizontal structural section impedes the utilization of overhead cranes for loading; instead, forklifts and other lateral lifting devices are utilized.
A series of risers are provided on the deck of the prior art centerbeam railcar. The risers are slightly declined toward the center partition. Vertical posts which make up the center partition are tapered as they extend upward from the deck of the railcar. When lumber and drywall and loaded onto the declined risers, they "lean into" the center. The deck of the car has very little strength between the risers and the risers themselves are not designed to handle especially concentrated loads, since lumber and drywall loads are distributed equally on the risers and along the full length of the car.
Altogether different railcars are utilized for the hauling of steel beams. Short beams are hauled in gondolas or on short bulkhead flat railcars. The longer beams are hauled on very long flat cars. The decks of these cars must be heavily reinforced to allow the loading of the various lengths of steel beams. Unlike lumber loads, loads of steel beams are not generally uniformly distributed. Additionally, the bulkheads utilized in steel-carrying cars must be designed for the extreme impact generated by the movement of the steel beams.
In general, railcars are relatively expensive to purchase and maintain. The profitability of a railroad is determined in substantial part by the efficiency of operation. Efficiency can be increased by minimizing the total number of cars required to meet all of the customers' needs. Additionally, efficiency can be increased by minimizing the transport of empty cars, whenever possible. Profitability may also be increased by facilitating the ease with which loads are loaded or unloaded from railcars, thus speeding up such operations. Additionally, minimizing the possibility of damage to transported articles in transit or in loading can also affect profitability.